1. Field
The present disclosure relates to materials with oxygen ionic conductivity, and more particularly, to a composite metal oxide with oxygen ionic conductivity. The composite metal oxide with oxygen ionic conductivity, for example, may be used as solid electrolyte and electrode material of a solid oxide fuel cell (“SOFC”). For other example, the composite metal oxide with oxygen ionic conductivity may be used in an oxygen sensor, an oxygen pump, and an oxygen permeating membrane.
2. Description of the Related Art
An SOFC unit cell includes a solid electrolyte and an electrode. Accordingly, the electrical characteristics of the solid electrolyte and the electrode are closely related to the performance of the SOFC. In particular, the ionic conductivity of the solid electrolyte and the ionic conductivity of the electrode material are important factors that determine the ohmic resistance and polarization resistance of the SOFC unit cell. Therefore, research has focused on the development of ion conductive materials for decades. Mixed oxides which have been suggested as materials for the solid electrolyte and electrode material of an SOFC usually have high electron mobility and high hole mobility but low oxygen ion mobility. Thus, only few materials with suitable ion conductivity have been discovered. Some materials with high ionic conductivity include those having a fluorite structure such as YSZ (yttria-stabilized zirconia: Y-doped ZrO2), CSZ (Ca-doped ZrO2), and GDC (Gd-doped CeO2). Other materials with high ionic conductivity include those having a Perovskite structure such as LSGM (Sr, Mg-doped LaGaO3).
Thus, there remains an unmet need for materials having improved oxygen ion conductivity.